Create a Linux Router with DHCP services

It’s pretty easy to build a Linux router even on a virutal machine. I’ve used virtualbox to create a LAN NAT router with DHCP services using webmin. However, I’m not going to cover on how to use a virtualbox VM 🙂

Let’s create the NAT Router first.

On Webmin go to Networking > Network Configuration > Routing and Gateways

Fig-1

1. Select right ethernet interface on Default Route
2. Fillup the correct gateway
3. Enable “Act as a Router”

On Networking > Linux Firewall > Select “Reset Firewall”

1. Do network address translation on external interface: <select your WAN interface>
2. Click Setup Firewall
3. Finally “Apply Configuration”

Your Linux NAT router is now ready 🙂

Now Setting up simple DHCP Server using Webmin

Install DHCP server

Option A): Centos 5.8

# yum  install  dhcp

Set the DHCP service to start on boot

# chkconfig  dhcpd  on

Start DHCP service

# service dhcpd start

Option B): Ubuntu 10.04

sudo apt-get install dhcp3-server

2.- Setting up

My network design is the following:

Network name: Intranet
Network adsress: 192.168.0.0
Netmask: 255.255.255.0
Address range: 192.168.0.75 – 192.168.0.150  (DHCP server can give 75 IPs)
Domain: mydomain.intranet
Default routers: 192.168.0.1
Broadcast address: 192.168.0.255
DNS servers: 192.168.0.21 80.58.61.250
192.168.0.21 -> DNS Server Local (our own DNS Server, within our network)
80.58.61.250 -> DNS Server External (ISP company)

Now do the following:

• Access webmin from any browser (use your own IP number):     https://your_IP:10000
• First refresh modules:   Webmin -> Webmin Configuration -> Refresh Modules
• Servers -> DHCP Server  – >  Add a new subnet.
• Fill boxes and click create
• Servers -> DHCP Server ->  Edit Client Options
• Fill boxes   (Antención with dot at the end of intranet!!!!!!!!)
• on the same screen mark Interim in “DNS update style” and click save
• Finally start DHCP server